Conventional solid-state switching devices such as RF switches, PIN switches, MESFET switches, and mechanical relays are used in a wide array of applications to control the conveyance and routing of electrical signals. In the field of microelectromechanical system (MEMS) devices, for example, such switching devices are used to perform rapid switching between RF and microwave signals in a phased array antennae or other phase shifting device. Such switching devices are also frequently used in the design of passive bandwidth microwave and RF filters, guidance systems, communication systems, avionics and space systems, building control systems (e.g. HVAC systems), process control systems, and/or other applications where rapid signal switching is typically required or desired.
The failure of many conventional switching devices remains a significant obstacle in the field, limiting both the reliability and actuation speed of the device. In the design of MEMS RF switches, for example, the repeated actuation of solid metal contacting surfaces can cause the device to fail or become unstable after a relatively short period of time (e.g. about 100 million cycles). In certain cases, failure of the device is caused by the presence of electrical arcs or sparks between the electrostatically actuated contact surfaces. Such arcing can cause the metal on the surfaces to melt and/or pit, causing stiction within the switch that can reduce contact reliability. Irregularities in the actuating surfaces can also cause jitter, resulting in variable switching times and an increase in the pull away force necessary to open the switch. In certain cases, the shape of the contact surfaces can also cause contact bounce, further reducing the efficacy of the device during operation. Other factors such as contact resistance (i.e. insertion loss), harmonics, parasitic oscillations, shock resistance, and temperature resistance may also limit the effectiveness of many prior-art switching devices.